The art of printing images with micro-fluid technology is relatively well known. A disposable or (semi)permanent ejection head has access to a local or remote supply of fluid (e.g., ink). The fluid ejects from an ejection zone to a print media in a pattern of pixels corresponding to images being printed. Accurately knowing fluid levels in supply items aids printing.
Yet, as printing evolves away from individual dedicated printers toward workgroup environments, users no longer man printers and note supply item volumes. If ink levels are incorrectly reported, network users potentially print pages before realizing empty supply items require replacement. Incorrect reporting also leads potentially to “dry firing” the ejection head and ingesting air in fluidic channels.
Also, ejection heads are now commonly separated from their ink source. While this helps reduce consumer costs by avoiding the repeated sale of silicon chips, and allows consumption of larger volumes of ink with fewer instances of replenishment, it necessitates the ink source to maintain some form of identification that it can report to printers. In turn, printers use the information to ascertain fluid levels, such as by counting algorithms in firmware that note drops ejected, firing commands initiated or other factors such as fluid evaporation over time. Printers notify users through sensors or display messages that their supply item is empty or nearing empty. Over the years, these algorithm schemes have ranged from slightly incorrect to exceptionally faulty. They have also proven ineffective upon fluid refilling. Users regularly ignore their results and warnings.
Still other detection schemes sense fluid by means of capacitors, optics, weight, ultrasound, magnets, floats, torque sensors, electrical probes, or the like. Many require some form of stimulus external to the supply item. The latter adversely complicates control systems between supplies and their corresponding printers. Many also involve one or more of the following: complex calibration schemes; process to ascertain variations in printer electronics and cabling tolerances; noisy signals resultant from lengthy conductive traces and remotely located circuit components; and inability to move supply items from one printing device to a next.
Accordingly, a need exists in the art to improve fluid level detection in supply items of imaging devices. The need extends not only to improving accuracy, but to simplicity in complex networked environments. Economic advantage is still another consideration. Additional benefits and alternatives are also sought when devising solutions.